Oilpan: fix build after r179341.

Source/web/WebDocument.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 255 matching lines @@
 }
 
 void WebDocument::setIsTransitionDocument()
 {
     // This ensures the transition UA stylesheet gets applied.
     unwrap<Document>()->setIsTransitionDocument();
 }
 
 void WebDocument::beginExitTransition(const WebString& cssSelector)
 {
-    RefPtr<Document> document = unwrap<Document>();
+    RefPtrWillBeRawPtr<Document> document = unwrap<Document>();
     document->hideTransitionElements(cssSelector);
     document->styleEngine()->enableExitTransitionStylesheets();
 }
 
 WebAXObject WebDocument::accessibilityObject() const
 {
     const Document* document = constUnwrap<Document>();
     return WebAXObject(document->axObjectCache()->getOrCreate(document->renderView()));
 }
 
@@ skipping 42 matching lines @@
     m_private = elem;
     return *this;
 }
 
 WebDocument::operator PassRefPtrWillBeRawPtr<Document>() const
 {
     return toDocument(m_private.get());
 }
 
 } // namespace blink